Best way to measure salt for new water?

[Jordon]

I weigh mine. Currently using Aquavitro Salinity and 333g is perfect for 2.5 gallons. This gives you 1.025 SG

I just use a digital kitchen scale. In fact I haven't used a refractometer regularly in a looooooong time, although maybe every 10 water changes or so test it just to be sure, and it's always been 100% accurate.